Propagation and Amplification of Rayleigh Waves and Piezoelectric Leaky Surface Waves in the Structure of InSb Thin Films on LiNbO3

Abstract

Analyses were conducted of the velocities and at- tenuation constants of piezoelectric leaky surface waves in LiNbOI with thin films. It was found that the effective electromechanical coupling coefficient K of leaky surface waves of 64' rotated Y-cut X-propagation LiNbOs with InSb thin films was very large; KZ = 0.120. The attenuation constant caused by radiation of energy into the solid is very small (O.O3O/X dB) when wh < loo0 m/s, where h is the thickness of the W. Moreover, we conhned by theories and experiments that the attenuation constants would go to zero at a certain thickness of the film. The K of Rayleigh waves of 131 rotated Y-cut X-propagation LiNbOa with thin 6lms is larger than that of Y-cut 2-propagation LiNbOa. Specifically, KZ has a maximum value of 0.260, when wh = 4500 m/s. Theroretical analyses and experiments on amplification with thin film semiconductors were performed for these waves. The InSb thin films were evaporated using source temperature programmed resistive heating method. Thin film drift mobility of 1250 cmZ/V-s was obtainedfor athickness of 500 A. An electronic gain of 32 dB/cm was achieved for an applied electric field of 1000 V/cm at 195 MHz.